Semiconductor (e.g., silicon) Temperature Sensors are calibrated to reduce the errors associated with the process-voltage-temperature (PVT) variations of silicon and the variations of analog circuits and components.
Silicon Temperature circuits are non-linear. Calibration can be used to compensate for non-linearaties, so that a linear analog-to-digital converter (ADC) can be used to approximate the temperature.
Analog trim have been used for this purpose. Implementing an analog trim technique involves expensive, high-precision analog test equipment and large circuit overhead.